Why not allow empty code blocks?

[neceros at gmail.com]

On Sunday, July 24, 2016 at 6:09:40 AM UTC-7, BartC wrote:
> On 24/07/2016 11:45, BartC wrote:
> > On 24/07/2016 11:35, BartC wrote:
> 
> > 'end' to terminate a block can be emulated of course:
> >
> > end=0
> >
> > def fn(a):
> >     if a<=1:
> >     return 1
> >     else:
> >         return fn(a-1)
> >     end
> > end
> 
> Actually this is a good example of how tabs can go wrong (and how the 
> tab system /is/ fragile - sorry but it is).
> 
> I almost certainly wrote the above using 4 and 8 spaces for the tabs, 
> except for the 'return 1' where I must have used an actual tab by 
> mistake. (And I tested it now by doing just that, and posting in alt.test.)
> 
> So the original /looked/ correct in my Thunderbird newsreader before I 
> posted. But after I posted, that tab somehow got changed to 4 spaces, as 
> it now looks wrong.
> 
> In this instance, the result won't compile. But it's not hard to imagine 
> a much larger program where that change would go unnoticed, and the 
> result is still valid code**.
> 
> Then anyone copying and pasting the posted code, would have a program 
> with a bug in it.
> 
> Mysteriously however, Chris Angelico's reply which quoted my post, 
> showed a properly tabbed version! (Unless he fixed it manually.)
> 
> (** Where working code has been posted, then Python will have picked up 
> inconsistencies where tabs and spaces are mixed. However take this code:
> 
> def fn():
> <tab>if a:
> <8 spaces>pass
> 
> This looks fine in my editor when <tab> is expanded to 4 spaces:
> 
> def fn():
>      if a:
>          pass
> 
> Python however doesn't like it (Python 2 doesn't anyway), because it 
> somehow assumes tabs expand to 8 spaces, so that the two indents look 
> like this to it:
> 
> def fn():
>          if a:
>          pass
> 
> So I can see a lot of problems whenever tabs are expanded differently:
> 
> a=1
> b=0
> 
> if a:
> <tab>if b:
> <tab><tab>print ("One")
> <8 spaces>print ("Two")
> 
> In my editor with 4-space tabs, it looks like the code will print 
> nothing as the two print lines are aligned within the 'if b:' block. But 
> in Python 2, it will print "Two". Python 3 more wisely reports the 
> inconsistency.)
> 
> -- 
> Bartc

Don't use tabs. Ever. It's simple.